Santiago is about 1.9 times smaller than Sydney.

Sydney (the 30 councils of metropolitan Sydney, without the Blue Mountains, Hawkesbury, Wollondilly and the Central Coast) is approximately 3,810 sq km, while Santiago (area of the 32 comunas of Santiago Province) is approximately 2,030 sq km, making Santiago 53.29% the size of Sydney.
Tip: This to-scale comparison of Sydney vs. Santiago uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.